Query String

The query string is a part of a URL that contains data and parameters to be passed to a web server. It is typically located at the end of a URL and starts with a question mark ?, followed by key-value pairs separated by ampersands &.

The values passed in the query string are available in the $_GET superglobal array. The keys of this array correspond to the names of the parameters in the query string, and the values are the corresponding values passed.

<?php

    // https://www.example.com/index.php?x=1

    print_r($_GET);
    Array(
        [x] => 1
    )

?>

Documentation

Related : Universal Resource Locator (URL), $_GET, Query